1. Field of the Invention
The present invention relates to a novel 2-anilinophenylacetic acid derivative possessing durable and strong valuable pharmacological effects with less side-effects and to a process for preparing the same. More particularly, the present invention relates to (5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl 2-(2,6-dichloroanilino)-phenylacetate possessing durable and strong valuable pharmacological properties accompanied by an extremely low level of side-effects and to a process for preparing the same.
2. Description of the Prior Art
From the past, a great number of non-steroid drugs have been developed as possessing anti-inflammatory, antipyretic, analgesic and/or anti-rheumatic activity. The drugs developed hitherto are generally classified into several groups; drugs of the salicylic acid series such as various aspirin preparations including bufferin, those of the anthranilic acid series such as mefenamic acid and flufenamic acid, those of the phenylacetic acid series such as alclofanac, diclofenac and fenbufen, those of the indole series such as indomethacin, those of the indene series such as sulindac, those of the heteroarylacetic acid series such as tolmecin, those of the propionic acid series such as ibuprofen, naproxen, ketoprofen and flurbiprofen, those of the prazolone series such as phenylbutazone, oxyphenbutazone, azapropazone, clofezone, ketophenylbutazone and succibutazone, those of the benzothiazine series such as piroxicam, those of the phenothiazine series such as metiazinic acid, those of the pyrimidine series such as bucolome, those of the indazole series such as benzydamine, those of pyrimidinylpyrazole series such as mepirizol, those of the thienopyridine series such as tinoridine hydrochloride, and those of the benzothiazolinone series such as tiaramid hydrochloride. However, these drugs are weak in their main pharmacological activities or concurrently exhibit relatively high toxicity in comparison with their main pharmacological activities so that a consecutive administration of the drugs over a long period of time will result in the occurrence of serious side-effects or drug-tolerance.
In the case of drugs of the salicylic acid series such as aspirin preparations, for example, the use in a smaller dose exhibits strong anti-inflammatory, antipyretic and analgesic activities while the use in a larger dose displays anti-rheumatic activity. On the other hand, however, the consecutive use of these drugs induces tinnitus and seriously attacks digestive organs and liver, especially the stomach. The use of drugs of the anthranilic acid series such as mefenamic acid exhibit analgesic activity but with poor anti-inflammatory activity and induces, on the other hand, lesion, diarrhoea and digestive system disorder. The use of drugs of the phenylacetic acid series possess relatively weak side-effects but exhibit only a medium degree of anti-inflammatory, antipyretic and analgesic activities. The use of drugs of the indole series such as indomethacin exhibits especially remarkable anti-rheumatic activity in addition to anti-inflammatory and analgesic activities but influences the central nervous system so as to cause headaches and giddiness and induces various side-effects including digestive system disorders. In the case of drugs of the indene series such as sulindac, the side-effects on the central nervous system as seen in the drugs of the indole series are almost eliminated but a medium degree of digestive system disorder still remains as side-effects. The use of drugs of the heteroarylacetic acid series exhibits strong analgesic activity but with digestive system disorders. The use of drugs of the propionic acid series such as ibuprofen is now recommended because of their weak side-effects. On the other hand, however, these drugs are not so strong in their main pharmacological effects although they possess anti-inflammatory, antipyretic and analgesic activities on the average. Drugs of the pyrazolone series such as phenylbutazone exhibit various pharmacological effects in addition to anti-inflammatory and analgesic activities but permit the occurrence of various side-effects including lesions, edema, blood dyscrasia, hepatic disorders and digestive system disorders. Drugs of the benzothiazine series exhibit rapid and durable anti-inflammatory, antipyretic and analgesic activities of medium degree but concurrently exhibit edema and digestive system disorders.
Thus, all of the drugs now commercially available as exhibiting anti-inflammatory, antipyretic and analgesic activities produce more or less side-effects. If such side-effects are substantially eliminated, the main pharmacological effects are in toto enhanced and the consecutive use of such drugs becomes possible to exhibit strong pharmacological activities. Accordingly, there is still great demand for developing a new compound which exhibits strong pharmacological activities with negligibly weak side-effects.